Weird phasiness on cable TV audio

For several months, I've been noticing a strange phenomenon on several of the cable channels on my local system. I really hear this happening on Comedy Central a LOT. Basically, when they go to commercial (and return) there is what sounds like a phase inversion happening to the audio. I can't tell if the audio is collapsing to mono or if the phase is flipping 180 degrees. Has anybody else noticed this or know what's causing it?

 

I've been hearing tis on Comedy Central for the last few months. It's annoying and I wish theyd stop it.

 

I should probably break out (and dust off) my O'scope and watch what happens to the waveform. It happens so consistently that it would be easy to catch but I'm not sure I could interpret what the scope was telling me. I'm sitting equidistant between a pair of Mackie HR824's and they image really well. The first time I heard this, I thought I was having a STROKE!

 

i've been hearing this as well...especially when an audience claps, etc. - sounds like some major "phasing/flanging" going on - what gives?

 

I haven't been watching Comedy Central in particular, but I hear a lot of audio compression artifacts across the span of cable, and it's even worse on DSS. If I hear what everyone else is hearing, the sound gets "swirly" like a bad mp3 or a digital answering machine.


Dan

 

I guess it's the curse of hanging out here and being more critical of sound in general. This same cable system had dropped the left channel of the Bravo Channel. I sent in several complaints and it was a couple months before they fixed it. They contacted me once to blame it on my equipment but they finally realized it was on their end. I don't know if this "phasiness" issue is something that is happening locally or if it is in the network feed. It's as clear as day when they go in and out of commercial. Hey Steve, if I hooked my the output channels to my scope, should it display as a "+" sign when it is in stereo?

 

It's sounds like a psuedo stereo widening effect. Sounds like crapola. I called Concast (misspelled intentionally), and they told me to upgrade to digital! Jerks.

jD

 

I watch TV in Pro Logic II mode and hear it.

It happens when they come back from commercials. After the commercial stops and the show begins about three seconds into the show there's a big flange that happens for about a second and then goes away.

It's really annoying. I watch the Daily show, well, uh, daily and it's like a water torture. After months of it I'm getting a little punchy.

 

Solved!

I too have been noticing this through several months. Over the summer I posted on a couple of technical boards I belong to and eventually something happened. I am going to check it tonight but I bet it is gone now. (or has been for a little bit) The explanation (I have quoted some of it below) fits the problem I was hearing to a "T".

(FYI MCR is master control room)
(AES is Audio Engineering Society and is a common digital audio format used for post production)
(DSK is down stream key-- which is used to put graphics over video--downstream meaning "at the end of the signal path" after all of the other keyers and effects--dissolves etc.)

 

I've noticed it particularly in The Daily Show, during the audience applause going back into the show from commercials. I'll bet there's an out-of-phase channel in their audio mixing board from one mic chain, because it just seems to happen during the seconds when the audience mics are up and they're just bringing the host mic up.

I noticed this the first week of The Colbert Report as well, but I haven't thought to make a note of it lately.

 

Oh, also our cable system one had the TBS audio out of phase for a couple of months before I was able to get an operator to understand what I was telling him, and let me leave a personal message to the engineering department.

 

fixed

Did you read my previous post? It explains what the problem was.

 

I have been wondering about that for a long time, as I used to be a foley engineer and am familiar with phasing and how it manages to get into the finished film product, I couldn't possible imagine how it got onto Comedy Central. Thanks sevenspot! I have something to impress my sound geek friends with now.

 

...audio is just the squeaky part of the picture!

 

The cable companies are often horrible as far as keeping their head ends set up right. When I had cable here, we had one channel that was about 10db too hot and all distorted. It was like that for months. It was not a major channel but still. I called several times and got nowhere. I happened to be working on a project for a client who is a large homebuilder who gets free cable, since he put it in his new homes. We were doing some tricky stuff like converting scrambled channels to clear channels in a subsystem using hardline fittings and pro processors from the cable company. We did this so this guy didn't need cable boxes in all his rooms to watch the pay channels. This was a 26,000 sq ft house with lots of rooms and TV's. As a result I had occasion to deal with the headend engineers. I pointed out the overloaded channel to them and they had no idea. We went in and trimmed it right on the spot. Also there was a bit of fake stereo on some channels which causes all kinds of issues.

How hard is it for a major cable company to monitor their channels?

I had many issues with my local cable company at my last house when they first started up in 1981. They were having all kinds of problems with stereo. At first they were modulating it on FM to simulcast MTV and some other channels. It was all compressed and sounded horrible. These guys had no clue. I ended up going to their headend and improving things considerably for them. I didn't do it for them. I did it so I could hear things right at home. These guys should have known how to do this stuff. Granted it was all new to them back then. At least I got some work out of it.